First try to get a better performance through increasing the tcp receive space:
Code:
# sysctl net.inet.tcp.recvspace=65535
net.inet.tcp.recvspace: 32768 -> 65535
You could try 4.5 and/or the latest and greatest snapshot.
What is the output of
ifconfig -A? What do
netstat -in and
netstat -ss report after some downloads?
BTW an easy way to install another version is to download the
bsd.rd file and do an ftp install. See
http://openbsd.org/faq/faq4.html#bsd.rd